Impacts of Rain and Waterlogging on Traffic Speed and Volume on Urban Roads

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Abstract: Rain causes significant drops in traffic speed and volume. Heavy rain can induce road waterlogging especially in the developing countries due to their poor drainage systems, which will exacerbate its effect on transportation systems. 45 urban waterlogging segments in Shenzhen, China are examined in this paper to quantify the effects of rainfall and rain-induced waterlogging on the traffic speed and volume using both descriptive and statistical methods. Results indicate that drops in travel speed and volume caused by waterlogging (-21.5 % to -24.3%, -25.8% to -31.2% respectively) is generally greater than rain (-1.2% to -18.4%, -1.1% to -16.5% respectively). It is also found that reductions in volume during the off-peak period are generally greater than those during peak hours however an opposite pattern is observed for speed. This research provides the intelligent transportation system with detailed information which is helpful for early warning, risk management and weather-responsive transportation management strategies devisal under rainy and waterlogging conditions. Further research might focus on the connections between research findings and their applications in the ITS context.